International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 10, October - 2013 Theoretical Survey on Secure Hash Functions and issues K. Saravanan 1 and A. Senthilkumar 2 1 Research scholar, Anna University Chennai and Assistant Professor, Department of Electronics and Communication, Nehru institute of technology, Coimbatore, Tamilnadu, India 2 Professor and Head, Department of Electrical and Electronics, Dr. Mahalingam college of Engineering and Technology, Pollachi, Tamilnadu, India Abstract H: {0, 1}* → {0, 1} n Security is a very important issue, which has attracted the interest In this notation, {0, 1}* refers to the set of binary elements of the research community, at a great factor. Hash functions of any length including the empty string while {0, 1} n belong to the category of encryption algorithms and are included refers to the set of binary elements of length n. Thus, the in almost all cryptographic schemes and security protocols for hash function maps a set of binary elements of arbitrary providing authentication services. Cryptographic hash functions are primitives and building blocks that are used to provide length to a set of binary elements of fixed length. information security. A cryptographic hash function is one which As mentioned earlier, hash functions are used in certain converts an input data of arbitrary length into a fixed-length information security schemes like password storage output. Bloom filters are hash based structures which have a application, digital signatures, Message Authentication certain degree of accuracy for considerable savings in memory. Codes (MACs) and digital image watermarking. In Research is being done to increase the performance by modifying password storage application, the password entered by a the structure of hash functions and enabling it to operate in the user at the first log-in is not stored in the computer system; increasing network speeds, thus variant Hashing algorithms are rather the hash of the password is stored. In digital being introduced. The aim of this paper is to survey the signatures, hash functions are used to improve the cryptographic hashing algorithms and applications to benefit the research community. efficiency (speed) and reduce the bandwidth of the scheme. The digital signature provides a means of demonstrating Keywords: Security, Hash function, Cryptographic hashIJERT IJERTthe authenticity of a message. A Message Authentication function, signature, FPGA. Code (MAC) can be used to verify that a received message is identical to the one that was sent. That is, it can be used to verify that a message has not been corrupted or 1. Introduction manipulated in transit. Another important application of hash functions is found in digital image watermarking. Hash function gained high significance for their role in Digital image watermarking is the process of embedding effective mapping of elements in hash tables. Basic information into a digital image. This serves the purpose of functions of hash tables are insertion, look-up and deletion facilitating the detection of image manipulation. of data records. Various applications of hash function are digital signature, data integrity, password verification and other cryptographic protocols. Cryptographic hash 2. SHA algorithms functions are primitive building blocks utilized in the schemes that are used to provide information security. The The SHA [2] series of algorithms stand for “Secure Hash cryptographic hash functions on their own do not typically Algorithm” they were developed by NIST. Due to the provide full information security; however, they play a avalanche effect even a small change in the data to be critical role in the schemes that do provide information encrypted will probably result in a very different hash security. Hence the security and speed of the cryptographic string. Because the SHA algorithms show signs of the hash function can significantly impact the overall security avalanche effect they are believed to have quite a good and computational efficiency of an information security randomization feature. SHA algorithms were based upon scheme. A cryptographic hash function is one which the MD4 and MD5 algorithms developed by Ron Rivest. converts an input data of arbitrary length into a fixed- SHA was released by the national security authority as a length output. Mathematically, a hash function [1] is US government standard. defined as follows, IJERTV2IS100449 www.ijert.org 1150 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 10, October - 2013 2.1 SHA-0 4. Haval hash function SHA-0 is officially known as SHA, it was the first HAVAL is a one-way hashing algorithm that produces incarnation of the secure hashing algorithm. This first output message digests of 128, 160, 192, 224 and 256-bits version was withdrawn soon after release due to [4]. The 1024-bit input message has different number of weaknesses in the design. SHA-1 was released a couple of passes that can be 3, 4, or 5. Combination of the two years later that fixed these problems. variable parameters, pass and output length, provides different levels of security. Two messages will collide each 2.2 SHA-1 other when they are compressed to the same message digest. There are two possibilities for a pair of message to collide in a HAVAL function: the number of passes the SHA-1 is a popular hashing algorithm released in 1994, messages is processed can be the same or differ and also and was developed by NIST. SHA-1 is similar to MD4 and like many others hashing algorithms HAVAL could not be MD5 hashing algorithms, and is more secure Also it is formally proved to be secure. HAVAL operation defines at considered as MD5’s successor. SHA-1 produces a 160 bit least three passes. hash. The SHA-1 algorithm is featured in a large number of security protocols and applications. 5. Tiger hash function 2.3 SHA-2 Tiger [5] is a cryptographic hash function proposed by Anderson and Biham in 1996. This hash function SHA-2 is based closely upon the SHA-1 Algorithm. SHA- processes 512-bit blocks and produces a 192-bit hash 2 actually combines the SHA-224, SHA-256, SHA -384 value. The tiger hash function uses a block-cipher-based and SHA-512 algorithms. compression function and the Davies- Mayer-type feed- forward structure [6].The 8-bit input and 64-bit output S- boxes of Tiger for the compression function provide faster 3. MD hash functions diffusion in comparison with integer arithmetic. It consists of two blocks namely, key schedule and state update The MD [3] family of hashing algorithms was designed by transformation block. The key schedule is an invertible Ron Rivest during the late 1980’s and early 1990’s. MD function in which changing a small number of bits in the actually stands for Message Digest. message will affect a lot of bits in the next pass. In state 3.1 MD2 IJERTupdate transformation of Tiger hash function, in each eight IJERTrounds, one 64-bit word X is used to update the three state variables (A, B and C). MD2 was optimized to run on 8-bit computers and The basic attack strategy on Tiger, based on the work of generates a 128-bit hash value. The hashes are Kelsey and Lucks on round -reduced variants involves the generally displayed as hexadecimal string which is following steps: Finding a good Characteristic for the Key 32 characters long. Schedule of Tiger and Message Modification by Meet-in- the-Middle. 3.2 MD5 6. Cuckoo hash function It is basically a secure version of MD4 which is a little faster than MD5.MD5 has been widely used as a secure Cuckoo Hashing [11] is a dynamization of a static hash algorithm particularly in Internet-standard message dictionary .The dictionary uses two hash tables, T1 and T2, authentication. The algorithm takes as input a message of each consisting of r words, and two hash functions h1, h2 : arbitrary length and produces as output a 128-bit message U = {0 . r −1}. Every key x, two values are stored either digest of the input.MD5 hash function is mainly intended in cell h1(x) of T1 or in cell h2(x) of T2, but never in both. for digital signature applications. The processing involves Cuckoo Hashing function method insertion and deletion is the following steps: padding, appending length, initialize used to move the keys either to the table or from the table. the MD buffer, process message in 16-word blocks and It is based on the possibilities of the moving keys. Two output function. way hashing method are used to two instances of Chained hashing. A key is inserted in one of the two hash tables, namely the one where it hashes to the shorter chain. If the IJERTV2IS100449 www.ijert.org 1151 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 10, October - 2013 chain is long re-hash is needed. Finally the large amount of types which are, JH-224, JH-256, JH-384 and JH-512 and space size is needed for dynamic perfect hashing. all these types use the new compression function,F8.For every input message block, a 1024-bit output is generated that is truncated producing a message digest with 224 (JH- 7. Whirlpool hash function 224), 256 (JH-256), 384 (JH-384) or 512 bits (JH-512). The JH hash function consists of five steps, which are: The Whirlpool hash function [7] was chosen as part of the Padding the initial message, M, passing the padded New European Schemes for Signatures, Integrity and message into message blocks, setting the initial hash value, Encryption (NESSIE) in February 2003.The Whirlpool H(0), computing the hash value H (N) and finally hash function produces an output of 512-bits and has been generating the message digest by truncating H (N).